Gulls of August

Black-tailed Gull

Shinano River, Niigata City, Niigata, Japan

August 2016

We seem to get different waves of gulls at different times of the year in Niigata. April is a good time for Black-headed Gulls but at most other times I think it is mostly Black-tailed Gulls and Common Gulls. What I can figure out from my field guides anyway. I keep saying to myself that I should follow them up more. I think they have interesting stories. At the hottest times in summer and their tails are pretty worn. I wonder if they do that to each other or whether crows play a part as I have seen crows chopping at Black-eared Kites' tails in the summer. 

I makes it more difficult to identify them:

Compare this to the one below. I think this may be a Common Gull...?